Silicon carbide (SiC) has a wide band gap, high maximum breakdown electric field and high thermal conductivity compared to those of silicon (Si), carrier mobility almost as high as that of silicon, high saturated electron drift velocity and high withstand voltage. Silicon carbide is thus expected to be applied to semiconductor devices required to have higher efficiency, higher withstand voltage, and higher capacity.
One of such semiconductor devices known is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) of SiC (Non-Patent Document 1, for example). Non-Patent Document 1 discloses that, when MOSFETs are fabricated on the (11-20) plane of a SiC substrate, a drain current along the <1-100> direction is 3 times larger than along the <0001> direction. It is known that a crystal orientation (plane orientation) has a strong influence on electron mobility even when MOSFETs are fabricated on the same plane, as described above.